feat: add /undo-patch endpoint

Author: MiniDigger

src/main/java/io/papermc/patchroulette/controller/RESTController.java

@@ -115,6 +115,18 @@ public ResponseEntity<String> cancelPatch(@RequestBody final PatchId input) {
         return ResponseEntity.ok("Patch cancelled.");
     }
 
+    @PreAuthorize("hasRole('PATCH')")
+    @PostMapping(
+            value = "/undo-patch",
+            consumes = "application/json",
+            produces = "text/plain"
+    )
+    public ResponseEntity<String> undoPatch(final Authentication auth, @RequestBody final PatchId input) {
+        final String user = this.getUser(auth);
+        this.patchService.undoPatch(input, user);
+        return ResponseEntity.ok("Patch moved to WIP.");
+    }
+
     @PreAuthorize("hasRole('PATCH')")
     @PostMapping(
 		value = "/login",

src/main/java/io/papermc/patchroulette/service/PatchService.java

@@ -78,6 +78,17 @@ public void finishWorkOnPatch(final PatchId patchId, final String user) {
         this.patchRepository.save(patch);
     }
 
+    @Transactional
+    public void undoPatch(final PatchId patchId, final String user) {
+        final Patch patch = this.patchRepository.getReferenceById(patchId);
+        if (patch.getStatus() != Status.DONE) {
+            throw new IllegalStateException("Patch " + patchId + " is not DONE");
+        }
+        patch.setStatus(Status.WIP);
+        patch.setResponsibleUser(user);
+        this.patchRepository.save(patch);
+    }
+
     public void clearPatches(final String minecraftVersion) {
         this.patchRepository.deleteAllByMinecraftVersion(minecraftVersion);
     }